I. Field of the Invention
This invention relates to network planning and deployment of position location networks. More specifically, this invention relates to evaluating the performance of a system for position location services.
II. Description of Related Art and General Background
Wireless systems for mobile communications include such examples as cellular telephone networks, broadband Personal Communication Services (PCS), wireless local-area networks (LANs), satellite communication systems, and two-way radio systems. These systems include mobile units that may be telephone or radio handsets, vehicle-based transceivers, wireless data modems, or even semi-fixed units such as wireless local loop (WLL) stations. Many such systems also have an infrastructure including one or more base station units whose locations are fixed and which communicate with the mobile units and possibly also with each other and/or an external network. In a cellular telephone network, for example, the base station units provide an interface between the mobile units and the public switched telephone network, communicate with registries to perform authentication and billing functions, and may also interact with each other to perform call management and handoff functions.
It is desirable to augment certain wireless systems for mobile communications by adding the capability to locate the position of a particular mobile unit. One reason is a regulation promulgated by the Federal Communications Commission (Docket No. 94-102, Third Report and Order adopted Sep. 15, 1999, released Oct. 6, 1999) which requires all cellular carriers in the United States to be able to locate the position of a cellular telephone making a 911 call within 50 meters for 67 percent of calls and within 150 meters for 95 percent of calls by October 2001. Other uses for position location capability in wireless communications systems include value-added consumer features such as navigation and vehicle fleet management support.
Several different approaches to position location may be implemented. These approaches include but are not limited to terrestrial methods, Global Positioning System (GPS) methods, and hybrids of terrestrial and GPS methods. The relative performances of these approaches as applied to any particular system for wireless communications will depend to some extent on the characteristics of that system and of the region where the system is deployed. Hence, it is desirable to be able to evaluate the performance of one or more such approaches within a system before a commitment is made to adopt or implement any particular approach. A need therefore exists for a method or apparatus that may be used to evaluate the performance of an existing or proposed wireless communications system with respect to position location. It is also desirable to be able to compare the performances of several different approaches to position location, whether during the planning and design stages for a new system or during upgrading or troubleshooting of an existing system.
In an apparatus according to an embodiment of the invention, a structured collection of information (such as one or more among databases, arrays, matrices, or compilations) is provided which relates to a target region. At least one processing unit is also provided which processes at least a part of the structured collection of information. Information is thereby produced by the processing unit or units that relates to the position of a mobile or stationary wireless unit within the target region.